In the past few years, many cities and local governments have embraced bicycling as a reasonable way to use public roads — carving out special lanes, setting up bike-sharing stations and generally making life easier for those who want to travel by two wheels rather than four. But those moves haven't come without complaint about congestion and special treatment, and just as biking clubs have grown for weekend riders, so has anti-bike advocacy and concerns about who rules the road — such as the handmade warning signs above from a pro-vehicle group. In a shocking but not surprising turn, one...